Metal-insulator-metal device

ABSTRACT

A method for forming a metal-insulator-metal device includes imprinting at least one first layer to form a first impression, removing a portion of at least one second layer through the first depression to form a recess in the at least one second layer bordered by a first side, a first overhang along the first side, a second opposite side and a second overhang along the second side. The method also includes depositing a first metal in the recess spaced from the first side and the second side and oxidizing the first metal to create a non-linear dielectric.

BACKGROUND

Metal-insulator-metal (MIM) devices may be used in a variety ofdifferent applications such as displays. Many processes used tofabricate MIM devices may require multiple steps which are sometimesdifficult to control. For example, many processes require complex,multi-step lithographic processes. In many processes, it is alsodifficult to control and minimize the size of the MIM device. In manyprocesses, materials forming the MIM device are exposed to highertemperatures, limiting the use of materials that are heat resistant orthat are capable of withstanding such higher temperatures. As a result,many MIM devices are relatively expensive and large.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a display incorporating MIMdevices according to one exemplary embodiment.

FIG. 2 is a schematic illustration of a single MIM device according toone exemplary embodiment.

FIG. 3 is a schematic illustration of a dual MIM device according to oneexemplary embodiment.

FIG. 4 is a top plan view of a MIM backplane according to one exemplaryembodiment.

FIG. 5 is a sectional view schematically illustrating coupling of anembossing layer and a sacrificial layer upon a carrier substrateaccording to one exemplary embodiment.

FIG. 6 is a sectional view schematically illustrating embossing orimprinting of the at least one embossing layer according to oneexemplary embodiment.

FIG. 7 is a sectional view schematically illustrating the imprintedembossing layer having a formed channel according to one exemplaryembodiment.

FIG. 8A is a sectional view illustrating exposing of the sacrificiallayer through the channel according to one exemplary embodiment.

FIG. 8B is a top plan view of the layer of FIG. 8A according to oneexemplary embodiment.

FIG. 9 is a sectional view illustrating removal of portions of thesacrificial layer through the channel to form a recess having first andsecond side edges according to one exemplary embodiment.

FIG. 10 is a sectional view illustrating deposition of a first metal inthe recess and spaced from the first and second side edges according toone exemplary embodiment.

FIG. 11 is a sectional view schematically illustrating anodization ofthe first metal within the recess to form non-linear dielectric portionsaccording to one exemplary embodiment.

FIG. 12 is a sectional view illustrating removal of the first metal fromthe embossing layer according to one exemplary embodiment.

FIG. 13A is a sectional view illustrating further removal of portions ofthe embossing layer and the sacrificial layer according to one exemplaryembodiment.

FIG. 13B is a top plan view of the layers of FIG. 13A according to oneexemplary embodiment.

FIG. 14 is a sectional view illustrating annealing of the non-lineardielectric portions according to one exemplary embodiment.

FIG. 15A is a sectional view schematically illustrating forming of asecond metal on a first portion of the non-linear dielectric and formingof a third metal on a second portion of the non-linear dielectricaccording to one exemplary embodiment.

FIG. 15B is a top plan view of the layers of FIG. 15A according to oneexemplary embodiment.

FIG. 16 is a sectional view illustrating the coupling of a displaysubstrate according to one exemplary embodiment.

FIG. 17 is a sectional view illustrating separation of the carriersubstrate according to one exemplary embodiment.

FIG. 18 is a sectional view schematically illustrating electricallycoupling of an electrode to one of the second metal and the third metalaccording to one exemplary embodiment.

FIG. 19 is a sectional view schematically illustrating coupling of anelectro-optical media to the formed backplane to form a display.

In certain sectional views, selected lines or portions have been omittedfor ease of illustration.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

FIG. 1 is a schematic illustration of a display 20 which is shown as anactive matrix electro-optical display. Display 20 generally includeselectro-optical cells 22, MIM devices 24, addressing voltage driver 26,and video signal driver 28. Electro-optical cells 22 comprise individualcells arranged in a matrix or array and configured to alter or block thetransmission of light to produce a visual display or image. Each cell 22forms a pixel of display 20. Electro-optical cells 22 each generallyincludes an electro-optical media 32 which is configured to change lightaltering or blocking states in response to applied electrical charge orelectrical fields. In the particular example shown, electro-opticalmedia 32 includes liquid crystals. Each cell 22 additionally includes apair of electrodes 34, 36 in which the electro-optical media 32 issandwiched. In a transmissive display where a backlight is implemented,both electrodes 34 and 36 are transparent. In a reflective display, onthe other hand, the electrode 36 is transparent while the electrode 34is reflective. Electrodes 34, 36 apply an electrical field toelectro-optical media 32 to selectively vary and control thelight-altering or blocking nature or state of electro-optical media 32and of cell 22.

MIM devices 24 can be either a single MIM device or a dual MIM devicethat comprises two connected single MIM devices. Each single MIM deviceincludes a non-linear dielectric material sandwiched between a pair ofelectrically conductive metals. FIG. 2 schematically illustrates asingle MIM device 124 which includes a non-linear dielectric 135sandwiched between a pair of electrically conductive metals 137, 139.Because of the non-linear current/voltage characteristic, current doesnot flow before a threshold voltage is exceeded. Once the thresholdvoltage is exceeded, the MIM device presents relatively low impedance.The threshold voltage is observed in both applied polarities. Thus, theMIM devices serve as switches for selectively charging their associatedelectro-optical cells to produce a desired visual display. It should benoted that if the conductive metals 137 and 139 have different workfunctions or the interface of metal 137 and dielectric 135 iselectronically different from the interface of dielectric 135 and metal139, the single MIM device may have different threshold voltages inforward and reverse bias. Such a voltage difference may causeundesirable effects in displayed image and requires corrections indriver electronics.

FIG. 3 schematically illustrates a dual MIM device 224 which generallycomprises two connected single MIM devices. In particular, dual MIMdevice 224 includes non-linear dielectric materials 135 and 235sandwiched between electrically conductive metals 137, 139 andelectrically conductive metals 237, 239, respectively. As further shownby FIG. 3, the two single MIM elements or diodes are coupled in an“anti-series” arrangement such that electrically conductive metals ofthe same work-function are coupled to one another. In the particularexample shown, the electrically conductive metals 139 and 237, havingthe same work function and interface to the dielectric 135 and 236respectively, are connected together. The electrically conductive metals137 and 239 also have the same work function and interface to thedielectric 135 and 236, respectively. This configuration provides anability to cancel out the forward bias effects of one MIM device withthe reverse bias effects of another MIM device. Dual MIM device 224 alsohas a reduced capacitive coupling.

Addressing voltage driver 26 comprises an electronic componentconfigured to transmit electrical voltages to MIMs 24 via addressinglines 38, 40 as shown in FIG. 1. The addressing voltages transmitted bydriver 26 represent “select” and “non-select” conditions to switch eachMIM device 24 between an electrically conducting state and anon-conducting state. In one embodiment, the addressing voltagestransmitted via address lines 38 and 40 may be in the form of a squarewave. When the “select” condition is met, a particular MIM device 24 isturned into an electrically conducting state and its associatedelectro-optical material 32 may be charged based upon video signals fromdriver 28. Alternatively, when the “non-select” condition is met, aparticular MIM device 24 is turned into a non-conducting state and itsassociated electro-optical media 32 is not charged or addressed by videosignals from driver 28.

Video signal driver 28 comprises an electronic component configured totransmit video signals, in the form of electrical voltages, toelectro-optical media 32 via video signal lines 42, 44. The videosignals transmitted by driver 28 charge the electro-optical media 32 ofthose cells 22 that are being addressed, resulting from the associatedMIM 24 being actuated to a conducting state by driver 26.

In operation according to one scenario, addressing voltage driver 26transmits a “select” voltage to MIMs 24A and 24B via line 38 and at thesame time a “non-select” voltage to MIMs 24C and 24D via line 40. As aresult, MIMs 24A and 24B are actuated to conductive states, allowingelectro-optical media 32A and 32B to be addressed by video signalstransmitted from driver 28 via lines 42 and 44, respectively. The videosignals transmitted via lines 42 and 44 may be the same or distinct fromone another depending upon the display to be created.

Thereafter, addressing voltage driver 26 may transmit a “non-select”voltage to MIMs 24A and 24B via line 38 and at the same time a “select”voltage to MIMs 24C and 24D via line 40. As a result, MIMs 24C and 24Dare actuated to conductive states, allowing electro-optical media 32Cand 32D to be addressed and charged in response to receiving videosignals from video signal driver 28 via lines 42 and 44, respectively.Once again, the video signals being transmitted via lines 42 and 44 maybe the same or may be different depending upon the image being created.Upon being charged, electro-optical media 32A, 32B, 32C and 32D holdtheir respective states as other cells 22 and electro-optical media 32are addressed. This process is generally repeated until an entire matrixor array of cells 22 is addressed and actuated to achieve a desiredoptical output.

FIG. 4 is a top plan view of one example of a MIM backplane 410 for anindividual pixel of a display such as display 20. Backplane 410 includesdisplay substrate 414, the addressing voltage bus line 438, dual MIMdevice 424, and electrode 434. Display substrate 414 generally comprisesa structure supporting the bus line 438, dual MIM device 424, andelectrode 434. Substrate 414 is generally formed from dielectricmaterial such as glass or a flexible plastic or polymer. Examples of aflexible plastic or polymer that may be used include polyethyleneterephthalate (PET) or polyethylene naphthalate (PEN). In otherembodiments, one or more other materials may be used for formingsubstrate 414. Substrate 414 is generally adhered or bonded to the busline 438, dual MIM device 424, and electrode 434 by an adhesive such asNOA 81 by Norland Products, Inc. In the particular example shown,substrate 414 has a thickness of between about 50 micrometers and 200micrometers. The thickness of the adhesive layer extending betweensubstrate 414 and the remaining components of backplane 410 is betweenabout 5 micrometers and 20 micrometers. In other embodiments, the busline 438, dual MIM device 424, and electrode 434 may be coupled tosubstrate 414 in other fashions without the use of adhesive.

The bus line 438 comprise electrically conductive traces or lineselectrically coupled to addressing voltage driver 26 (shown in FIG. 1).Bus line 438 is electrically coupled to MIM device 424. The line 438transmits the addressing voltages from driver 26 to MIM devices 424 toactuate or bias such a MIM device between conducting and non-conductingstates.

In the particular embodiment shown in FIG. 4, the MIM device 424 is adual-MIM devices, such as the dual-MIM device 224 schematically shown inFIG. 3. MIM device 424 is electrically connected between bus line 438and electrode 434 and includes conductive metal portions 450, 452, 454and non-linear dielectric portions 456 and 458. Metal portions 450 and452 have boundary areas 437 and 439 between which is sandwichednon-linear dielectric 456. Conducting metal portion 452 and 454 haveboundary portions 537 and 539 which are both in contact with non-lineardielectric 458. Metal portion 450 is in electrical contact with addressbus line 438. Metal portion 454 is in electrical contact with electrode434. Upon the transmission of a “select” voltage to MIM device 424,non-linear dielectrics 456 and 458 become electrically conductive,allowing current to flow with little impedance through MIM device 424 toelectrode 434. Thus the MIM device 424 serves as a switch, enablingelectrode 434 and the associated electro-optical material 32 (shown inFIG. 1) to be selectively addressed depending upon the addressingvoltage transmitted via the bus line 438.

FIGS. 5–18 illustrate one example of a method for fabricating backplane410. The method shown in FIGS. 5–18 utilizes macro-area processingtechniques and does not require photolithography, reducing thecomplexity and cost for the fabrication of backplane 410. As shown inFIG. 5, an embossing layer 620 and a sacrificial layer 610 are coupledto carrier substrate 612. For purposes of this disclosure, the term“coupled” means the joining of two members directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two members or the two members andany additional intermediate members being integrally formed as a singleunitary body with one another or with the two members or the two membersand any additional intermediate member being attached to one another.Such joining may be permanent in nature or alternatively may beremovable or releasable in nature. Embossing layer 620 comprises a layerof one or more materials such that the layer may be embossed orimprinted upon by an embosser such as an embossing shim 622.

Sacrificial layer 610 comprises a layer of one or more dielectricorganic materials configured to be later removed or sacrificed in theformation of backplane 410. Sacrificial layer may comprise any materialhaving a differential etch rate. In one embodiment, sacrificial layer610 comprises a positive photoresist that, after exposure to UVradiation, can be dissolved by a solvent. In another embodiment,sacrificial layer 610 comprises a negative photoresist that may needmuch higher UV radiation dosage to be fully cured than that needed bythe embossing layer 620. In both cases, the sacrificial layer 610 can bepartially dissolved away by a solvent after the embossing layer 620 isfully cured. In the specific example illustrated, sacrificial layer 610has a relatively small thickness T₁ of less than 2 micrometers. In otherembodiments, sacrificial layer 610 may comprise doped semiconductors andmetals.

Carrier substrate 612 comprises an electrically conductive substrateconfigured to support sacrificial layer 610. In the example shown,carrier substrate 612 is provided as part of a roll-to-roll process,wherein carrier substrate 612 is wrapped about the reels 614, 616. Acarrier substrate may be formed from one or more conductive materialssuch as copper or nickel with a highly smooth surface finish and highconductivity. Carrier substrate 612 may comprise a bulk conductor, suchas a metal plate or sheet, or may comprise a dielectric sheet with aconducting surface layer.

According to one exemplary embodiment, carrier substrate 612 ispassivated to form a thin release layer 618. For example, the conductingsurface of carrier substrate 612 may be treated with 0.1 N potassiumdichromate aqueous solution for 10 minutes, followed by rinsing anddrying. Release layer 618 may be a very thin oxide, a surfactant layeror a monolayer polymer release agent. In those embodiments includingrelease layer 618, sacrificial layer 610 is formed upon the releaselayer 618. Release layer 618 is substantially conductive.

As further shown by FIG. 5, an embossing layer 620 is deposited uponsacrificial layer 610. Embossing layer 620 comprises a layer of one ormore materials such that the layer may be embossed or imprinted upon byan embosser such as an embossing shim 622.

FIGS. 6 and 7 illustrate the embossing or imprinting upon of embossinglayer 620 by embosser 622. As shown by FIG. 6, embosser 622 includes asurface relief 624. Surface relief 624 is configured to form featureswithin embossing layer 620 corresponding to address line 438 and MIMdevice 424. In the particular example shown, relief surface 624 includesprojections 626, 628 and 630. Projection 626 forms a channel 632 withinembossing layer 620 which generally corresponds to the outline ofaddress line 438 and metal portion 450. Projection 628 embosses orimprints a channel 634 within layer 620 which generally corresponds tothe outline or shape of metal portion 454. Projection 630 is configuredso as to project into layer 620 so as to form channel 636 whichgenerally has a shape or outline of the boundaries 439, 537 betweenmetal portion 450 and metal portion 454 as shown in FIG. 4. As indicatedby broken line 637 in FIG. 6, projection 630 may alternatively extendinto sacrificial layer 610 so as to also emboss sacrificial layer 610.

In the particular example shown, embossing layer 620 is formed from oneor more materials such that embossing layer 620 has a deformable shapeuntil treated. In the particular example shown, embossing layer 620comprises an optically transparent UV curable dielectric resin (e.g.,Norland Optical Products NOA83H). As a result, upon the application ofUV illumination, the shape of embossing layer 620 becomes stabilized. Inthe particular example shown, embosser 622 is substantially transparentto UV wavelengths. Once embosser 622 has been positioned into layer 620such that layer 620 takes up the form or shape of release surface 624 asshown in FIG. 6, UV illumination is applied through embosser 622 toembossing layer 620 to cure and solidify or stabilize the shape ofembossing layer 620 while embosser 622 is in place. Thereafter, as shownin FIG. 7, embosser 620 is separated from layer 620 to expose and revealchannels 632, 634 and 636.

In other embodiments, embossing layer 620 may comprise one or more othermaterials such that embossing layer 620 may be treated to stabilize theshape of embossing layer 620 by other means such as by heat, chemicalreactions, thermosetting reactions, curing or cross-linking, inductionheating, microwave and other forms of electromagnetic radiation and thelike, while embosser 622 is positioned into layer 620 or upon removal ofembosser 622 from layer 620. In still other embodiments, embossing layer620 may be provided by other materials which do not require treatment toachieve a stabilized shape or which require treatment to achieve adeformable state which naturally stabilizes and shapes over time orwhich may require further treatment for shape stabilization. Although inthe particular example illustrated, embossing layer 620 is formed fromone or more transparent materials, in other embodiments, embossing layer620 may alternatively be opaque such as in those embodiments in which atleast those portions of embossing layer 620 which overlie or underlieelectrical optical media 32 (shown in FIG. 3) are removed during themanufacture of the display in which backplane 410 is to be used.

FIGS. 8A and 8B illustrate further deepening of channel 636 so as toexpose sacrificial layer 610. In particular, floor 637 (shown in FIG.8A) of channel 636 is removed. Floor 637 may be desirable in thoseparticular applications where underlying areas produce topography ofsacrificial layer 610, embossing layer 620 or both. In particularapplications, underlying portions of sacrificial layer 610 may also beremoved with floor 637. Examples of methods that may be used to removefloor 637 so as to deepen channel 636 and expose layer 610 includeoxygen plasma etching, UV-ozone treatment and laser ablation for thoseembodiments using polymers. For those embodiments using other materialsfor sacrificial layer 610, such as metals and doped semiconductors,other methods may be used to remove floor 637 and to deepen channel 636to expose layer 610 such as reactive ion etching, wet etching or ionbeam milling. In particular applications, the embossing or imprinting oflayer 620 may be performed such that channel 636 omits a floor 637 andexposes layer 610.

FIG. 9 illustrates removal of portions of sacrificial layer 610 throughdepression 636 to form a recess 640 within sacrificial layer 610. Recess640 is bordered by side edges 642, 644. As further shown by FIG. 9,portions of layer 610 are removed so as to additionally form overhangs646, 648 along sides 642 and 644, respectively. Overhangs 646, 648 areprovided by portions of the material of embossing layer 620 extendingover recess 640 along a depression or channel 636. In particularembodiments, portions of overhangs 646, 648 may also include portions oflayer 610.

In the particular example illustrated, portions of sacrificial layer 610are removed by wet or dry etching. Other material removal techniques mayalternatively be utilized depending upon the materials of sacrificiallayer 610.

FIG. 10 illustrates depositing metal portion 452 in recess 640. As shownby FIG. 10, the metallic material being deposited to form metal portion452 may cover or coat at least portions 649 of embossing layer 620.Overhangs 646 and 648 substantially hinder the metallic material frombecoming deposited upon side edges 642 and 644. Overhangs 646 and 648create a discontinuity between portion 452 and material deposited uponportions 649. In addition, overhang 646 and 648 enable metal portion 452to be deposited within recess 640 while being spaced from side edges 642and 644. As a result, the deposition and patterning of metal portion 452may be performed with less expensive deposition techniques and is easierto control.

In the example shown in FIG. 10, the metallic material of portions 649and metal portion 452 may be deposited using such methods as thermalevaporation and sputtering. The material on portions 649 and formingmetal portion 452 comprise tantalum. In other embodiments, the metallicmaterial may comprise other metals whose oxides function as non-lineardielectrics such as niobium, titanium, copper, silver, aluminum, andtheir alloys. In the particular example shown, metal portion 452 has aminimum thickness T₂ of at least 50 nm to provide sufficient materialfor anodization (shown in the next step) and sufficient conductivity toallow electrical current flow when the MIM device 424 is in a conductingstate and a maximum thickness not exceeding the thickness of thesacrificial layer such that a lift-off process may be implemented. Inthe particular example shown, metal portion 452 has a thickness T₂ of100 nm. In other embodiments, metal portion 452 has other thicknesses.

FIG. 11 illustrates anodization of metal portion 452 to form non-lineardielectric layer 661 providing portions 456 and 458. Those portions ofmetal portion 452 that are not anodized or oxidized remain electricallyconductive. In particular, metal portion 452 is anodized using agalvanic cell utilizing conducting substrate 612 as an anode, a cathode658 of a suitable metal, such as platinum and a suitable electrolyte660. In the example shown, the electrolyte may comprise a citric acid.In other embodiments, electrolyte 660 may comprise a boric acid solutionwith pH adjusted to 7 by NH₄OH, ammonium tartrate, ammonium borate.Electrolyte 660 may also include other surfactants and/or buffermaterials.

In the particular example shown in which metal portion 452 comprisestantalum having an anodization coefficient of approximately 1.9 nm/volt,voltage source 662 applies a starting current density of approximately0.2 mA per centimeter squared. Voltage source 662 applies a relativelyconstant voltage using a potentiostatic technique to completeanodization of metal portion 452. The voltage applied by voltage source662 and the time that the anodization is performed at constant voltagedetermines the thickness of non-linear dielectric portions 456 and 458and the final threshold of MIM device 424 (shown in FIG. 15). In theparticular example shown, voltage source 662 applies a generallyconstant voltage of 35 volts for 30 minutes at the final stage whichresults in non-linear dielectric portions 456 and 458 having a thicknessof approximately 65 nm (456 and 458 are in the same layer). In otherembodiments, the voltage applied by voltage source 662 may be varied tovary the thickness of non-linear dielectric portions 456 and 458.Because the portion 649 is electrically disconnected from the carriersubstrate, no anodization occurs and no oxide forms there.

FIG. 12 illustrates removal of metallic material 649 (shown in FIG. 11)from portions of embossing layer 620. In the particular example shown,metallic material 649 is removed by etching such as with a dry etch or awet etch. The etching technique chosen provides a sufficientdifferential etch rate between the metallic material 649 and thenon-linear dielectric material of portions 456 and 458. In theparticular example shown, removal of metal 649 can be achieved bywet-etching using acid based solvents such as the solvent consisting of1 part 48% HF, 2 parts concentrated HNO3, and 1 part H2O. Alternatively,removal of metal 649 can be achieved by using dry-etching under CF4plasma.

FIG. 13A illustrates further removal of portions of embossing layer 620and sacrificial layer 610 to expose carrier substrate 612 and/or releaselayer 618. In particular, portions of embossing layer 620 andsacrificial layer 610 are removed using the same methods (includingoxygen plasma etching, UV-ozone treatment and laser ablation) that areused to remove floor 637 of channel 636 in FIG. 8A. The removal ofmaterial results in channels 632 and 634 in embossing layer 620,initially formed by imprinting as shown in FIGS. 8A and 8B, beingdeepened such that channels 632 and 634 extend through sacrificial layer610 to release layer 618 or carrier substrate 612 shown in FIG. 13B.

FIG. 14 illustrates heat being applied to non-linear dielectric portions456 and 458 to anneal portions 456 and 458. Annealing of portions 456and 458 improves electrical performance of MIM device 424 (shown in FIG.15A) by reducing current leakage.

FIGS. 15A and 15B illustrate forming address line 438 and metal portions450 and 454. In particular, metallic material is deposited withinchannels 632 and 634 (shown in FIG. 7). As its thickness increases, themetal layer will extend horizontally and cover some portions withinchannel 636 upon non-linear dielectric portions 456 and 458 to formmetal portions 450 and 454. The deposition timing should be controlledsuch that the areas where the metal portions 450 and 454 overlap withnon-linear dielectric portions respectively reach the design value. Itshould also be noted that metal portions 450 and 454 are spaced from oneanother and are electrically isolated from one another by non-lineardielectric portions 456 and 458.

In the particular example shown, the metals forming address line 438 andmetal portions 450 and 454 are deposited by electro-deposition orelectroplating. As shown by FIG. 15A, the electroplating is performed byusing electrically conductive carrier substrate 612, conductive releaselayer 618 as a cathode, an anode 668 of suitable material such asplatinum or nickel, an electrolyte 670 and a voltage source 672.Electrolyte 670 includes selective additives which in conjunction withthe voltage applied by voltage source 672 result in metal portions 450and 454 partially extending over and in contact with non-lineardielectric portions 456 and 458 as thickness of metal portions 450 and454 increases. The voltage applied by voltage source 672 is maintainedbelow the voltage threshold of non-linear dielectric portions 456 and458 such that portions 456 and 458 remain insulating. As a result,little or no metallic material is deposited between non-lineardielectric portions 456 and 458 such that metal portions 450 and 454remain electrically isolated from one another after the separation ofcarrier substrate 612 and release layer 618 (as shown in FIG. 17hereafter). In particular embodiments, if the electroformed metallicmaterials of metal portions 450 and 454 do not sufficiently adhere tonon-linear dielectric portions 456 and 458, a thin layer of adhesivemetal may be deposited upon non-linear dielectric portions 456 and 458prior to electroforming of metal portions 450 and 454. In such ascenario, the adhesive metal in those areas not subsequently covered bymetal portions 450 and 454 may be removed by laser ablation or etching.

In the particular example shown, metal portions 450 and 454 comprise oneor more metals that are capable of electrochemical deposition with goodconductivity such as nickel, copper, silver and gold. Metal portions 450and 454 have a thickness of no greater than the combined thicknesses ofthe embossing layer 620 and the sacrificial layer 610. In otherembodiments, other techniques may be employed for depositing themetallic material of metal portions 450 and 454. In other embodiments,metal portions 450 and 454 may have thicknesses greater than 10micrometers.

FIG. 16 illustrates coupling of a display substrate to address line 438,metal portion 450, metal portion 454, non-linear dielectric portions456, 458 and metal portion 452. According to one exemplary embodiment,display substrate 414 is coupled to address line 438 and MIM device 424by adhesive layer 480. According to one embodiment, adhesive layer 480has a thickness of between about 5 and 20 micrometers.

FIG. 17 illustrates separation of carrier substrate 612 and releaselayer 618. FIG. 18 illustrates the forming of electrode 34. In theparticular example shown, electrode 34 is formed by depositing atransparent electrically conductive material in electrical contact withmetal portion 454. In one embodiment, electrode 34 is formed from adoped polyethylenedioxythiophene dispersion known as PEDOT or PDOTavailable as Baytron “P” from Bayer Chemicals. The deposition ofelectrode 34 may be achieved utilizing coating methods such asspin-coating or lamination, and the patterning methods include laserpatterning or laser ablation or other patterning techniques.

FIG. 19 illustrates further steps towards completing the illustratedportion of display 320 by adding alignment layer 682, electro-opticalmedia 32, alignment layer 684, electrode or transparent conductor 36 anddisplay substrate 686. In the example shown in FIG. 19, theelectro-optical media 32 comprises liquid crystals and the molecularstructure of electro-optical media 32 is aligned to the substrate ofbackplane 410 utilizing one or more alignment layers, barrier layers andother applied treatments, collectively represented as alignment layer682. Electro-optical media 32 is also similarly aligned with displaysubstrate 686 and transparent conductor 36 using one or more alignmentlayers, barrier layers and other treatments, collectively referred to asalignment layer 684.

Display substrate 686 supports electrode 36 and includes electrodepatterning for electrode 36 which may or may not be similar to electrode34. According to one embodiment, display substrate 686 may be formed ina similar manner to the formation of address line 438 and backplane 410without the steps of anodizing portions of the metal layer to formnon-linear dielectrics and without the addition of metal portion 452between the non-linear dielectric portions. In other embodiments,display substrate 686 with electrode patterning may be formed in othermanners.

Although the present invention has been described with reference toexample embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, although different exampleembodiments may have been described as including one or more featuresproviding one or more benefits, it is contemplated that the describedfeatures may be interchanged with one another or alternatively becombined with one another in the described example embodiments or inother alternative embodiments. Because the technology of the presentinvention is relatively complex, not all changes in the technology areforeseeable. The present invention described with reference to theexample embodiments and set forth in the following claims is manifestlyintended to be as broad as possible. For example, unless specificallyotherwise noted, the claims reciting a single particular element alsoencompass a plurality of such particular elements.

1. A method for forming a metal-insulator-metal (MIM) device, the methodcomprising: imprinting at least one first layer to form a firstdepression; removing a portion of at least one second layer through thefirst depression to form a recess in the at least one second layerbordered by a first side, a first overhang along the first side, asecond opposite side and a second overhang along the second side;depositing a first metal in the recess spaced from the first side andthe second side; and oxidizing the first metal to create a non-lineardielectric.
 2. The method of claim 1 including separating the at leastone second underlying layer from a carrier substrate layer.
 3. Themethod of claim 1 including anodizing the first metal to oxidize thefirst metal.
 4. The method of claim 1 including: forming a second metalon a first portion of the non-linear dielectric; and forming a thirdmetal on a second portion of the non-linear dielectric, the third metalbeing spaced from the second metal.
 5. The method of claim 4 includingforming an electrically conductive layer on one of the second metal andthe third metal.
 6. The method of claim 4, wherein the second metal isformed by electroplating.
 7. The method of claim 4, wherein the thirdmetal is formed from electroplating.
 8. The method of claim 6, whereinthe electroplating voltage is below the conductive threshold of thenon-linear dielectric.
 9. The method of claim 4 including: imprintingthe at least one layer to form a second depression in communication withthe first depression, the second depression having a depth less than thefirst depression; and forming a fourth metal in the second depression,wherein the fourth metal extends adjacent to one of the second metal andthe third metal.
 10. The method a claim 1 including coupling a substrateto the second metal and the third metal.
 11. The method of claim 10,wherein the substrate includes a flexible polymer.
 12. The method ofclaim 10, wherein the substrate includes glass.
 13. The method of claim1, wherein the step of imprinting includes: positioning a shim into thefirst layer such that the first layer takes a form of the shim; treatingthe first layer to stabilize the form; and removing the shim from thefirst layer.
 14. The method of claim 13, wherein the shim issubstantially UV transparent, wherein the first layer is a UV curablematerial, wherein the shim is positioned into the first layer prior tocomplete curing of the material of the first layer and wherein treatingincludes applying UV illumination to the first layer through the shim.15. The method of claim 1, wherein the first metal includes at least oneof tantalum, niobium, titanium, copper, silver, aluminum, and alloysthereof.
 16. The method of claim 1, wherein the first layer istransparent.
 17. The method of claim 1 including coupling the firstlayer and the second layer to a carrier substrate.
 18. The method ofclaim 17, wherein the carrier substrate is wrapped about two reels. 19.The method of claim. 17, wherein the carrier substrate is electricallyconductive.
 20. The method of claim 19, wherein charge is applied to thecarrier substrate during anodization of the first metal.
 21. The methodof claim 19, including: forming a second metal on a first portion of thenon-linear dielectric; and forming a third metal on a second portion ofthe non-linear dielectric, the third metal being spaced from the secondmetal, wherein charge is applied to the carrier substrate as the secondmetal and the third metal are formed by electroforming.
 22. The methodof claim 17 including: forming a second metal on a first portion of thenon-linear dielectric; forming a third metal on a second portion of thenon-linear dielectric, the third metal being spaced from the secondmetal; and decoupling the carrier substrate from the first layer and thesecond layer after the forming of the second metal and the third metal.23. A method for forming a metal-insulator-metal device, the methodcomprising: imprinting at least one first layer to form a depressionpattern having a first channel, a second channel, a third channelconnecting the first channel and the second channel; removing a firstportion of the at least one second layer through the third channel;removing a second portion of the at least one second layer through thethird channel to create a first overhang along the side edges of thethird channel; depositing at least one first metal in the third channel;anodizing the at least one first metal to create a first non-lineardielectric in the third channel; forming a second metal in the thirdchannel and on a first portion of the first non-linear dielectric; andforming a third metal in the third channel and on a second portion ofthe first non-linear dielectric, the third metal being spaced from thesecond metal.
 24. The method of claim 23 including removing material todeepen the first channel through the at least one second layer after thestep of anodizing and before the step of forming the second metal in thefirst channel.
 25. The method of claim 23, wherein the step of formingthe second metal in the first channel includes electroplating.
 26. Themethod of claim 23, wherein the step of forming the second metal and thestep of forming the third metal include electroplating.
 27. The methodof claim 26, wherein an electroplating voltage is below a conductingthreshold of the first non-linear dielectric.
 28. The method of claim 23including coupling a substrate to the second metal and the third metal.29. The method of claim 28, wherein the substrate includes a flexiblepolymer.
 30. The method of claim 23, wherein the step of imprintingincludes: positioning a shim into the first layer such that the firstlayer takes a form of the shim; treating the first layer to stabilizethe form; and removing the shim from the first layer.
 31. The method ofclaim 30, wherein the shim is substantially UV transparent, wherein thefirst layer is a UV curable material, wherein the shim is positionedinto the first layer prior to complete curing of the material of thefirst layer and wherein treating includes applying UV illumination tothe first layer through the shim.
 32. The method of claim 23, whereinthe first layer is transparent.
 33. The method of claim 23 includingcoupling the first layer and the second layer to a carrier substrate.34. The method of claim 33, wherein the carrier substrate is wrappedabout two reels.
 35. The method of claim 33, wherein the carriersubstrate is electrically conductive.
 36. The method of claim 35,wherein charge is applied to the carrier substrate during anodization ofthe at least one first metal.
 37. The method of claim 35, wherein chargeis applied to the carrier substrate as the second metal and the thirdmetal are formed by electroplating.
 38. The method of claim 33 includingdecoupling the carrier substrate from the first layer and the secondlayer after the forming of the second metal and the third metal.
 39. Amethod for forming a display, the method comprising: imprinting at leastone first layer to form a first depression; removing a portion of atleast one second layer through the first depression to form a recess inthe at least one second layer bordered by a first side, a first overhangalong the first side, a second opposite side and a second overhang alongthe second side; depositing a first metal in the recess spaced from thefirst side and the second side; anodizing the first metal to create afirst metal conductive portion and a non-linear dielectric; forming asecond metal on a first portion of the non-linear dielectric; forming athird metal on a second portion of the non-linear dielectric, the thirdmetal being spaced from the second metal; and electrically connectingone of the second metal and the third metal to electro-optical media.40. The method of claim 39, wherein the step of electrically connectingincludes forming a layer of electrically conductive material upon saidone of the first metal conductive portion, the second metal and thethird metal.
 41. The method of claim 40, wherein the electricallyconductive material is substantially transparent.
 42. The method ofclaim 39, wherein the electro-optical media includes liquid crystals.43. The method of claim 39 including coupling the first layer and thesecond layer to a carrier substrate.
 44. The method of claim 43, whereinthe carrier substrate is wrapped about two reels.
 45. The method ofclaim 43, wherein the carrier substrate is electrically conductive. 46.The method of claim 45, wherein charge is applied to the carriersubstrate during anodization of the first metal.
 47. The method of claim45, wherein charge is applied to the carrier substrate as the secondmetal and the third metal are formed by electroplating.
 48. Ametal-insulating-metal device formed by: imprinting at least one firstlayer to form a first depression; removing a portion of at least onesecond layer through the first depression to form a recess in the atleast one second layer bordered by a first side, a first overhang alongthe first side, a second opposite side and a second overhang along thesecond side; depositing a first metal in the recess spaced from thefirst side and the second side; and oxidizing the first metal to createa non-Linear dielectric.